linux-kernel - Re: [PATCH v15 07/11] drm/mediatek: Add retry to prevent misjudgment for sink devices

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Date:   Thu, 28 Jul 2022 17:40:41 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        <chunkuang.hu@...nel.org>, <p.zabel@...gutronix.de>,
        <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <matthias.bgg@...il.com>, <deller@....de>,
        <airlied@...ux.ie>
CC:     <msp@...libre.com>, <granquet@...libre.com>,
        <jitao.shi@...iatek.com>, <wenst@...omium.org>,
        <ck.hu@...iatek.com>, <liangxu.xu@...iatek.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-fbdev@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v15 07/11] drm/mediatek: Add retry to prevent
 misjudgment for sink devices

On Wed, 2022-07-27 at 11:40 +0200, AngeloGioacchino Del Regno wrote:
> Il 27/07/22 06:50, Bo-Chen Chen ha scritto:
> > For some DP dungles, we need to train more than onece to confirm
> > that we
> > don't misjudge the status of sink device.
> 
> Please fix the typos in your commit title and description.
> title: misjudgment -> misjudgement
> desc: dungles->dongles; onece->once
> 
> > 
> > Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_dp.c | 21 ++++++++++++++++++---
> >   1 file changed, 18 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> > b/drivers/gpu/drm/mediatek/mtk_dp.c
> > index ce817cb59445..80d7d6488105 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> > @@ -42,6 +42,7 @@
> >   #define MTK_DP_CHECK_SINK_CAP_TIMEOUT_COUNT 3
> >   #define MTK_DP_TBC_BUF_READ_START_ADDR 0x08
> >   #define MTK_DP_TRAIN_DOWNSCALE_RETRY 8
> > +#define MTK_DP_TRAIN_CLEAR_RETRY 50
> >   
> >   struct mtk_dp_train_info {
> >   	bool tps3;
> > @@ -1431,11 +1432,25 @@ static int mtk_dp_video_config(struct
> > mtk_dp *mtk_dp)
> >   
> >   static int mtk_dp_training(struct mtk_dp *mtk_dp)
> >   {
> > +	short max_retry = MTK_DP_TRAIN_CLEAR_RETRY;
> >   	int ret;
> >   
> > -	ret = mtk_dp_train_start(mtk_dp);
> > -	if (ret)
> > -		return ret;
> > +	/*
> > +	 * We do retry to confirm that we don't misjudge the sink
> > status.
> > +	 * If it is still failed, we can confirm there are some issues
> > for the
> > +	 * sink device.
> > +	 */
> > +	do {
> > +		ret = mtk_dp_train_start(mtk_dp);
> > +		if (!ret)
> > +			break;
> > +	} while (--max_retry);
> > +
> > +	dev_info(mtk_dp->dev, "dp training clear retry times: %d\n",
> > +		 MTK_DP_TRAIN_CLEAR_RETRY - max_retry);
> 
> dev_dbg() here.
> 
> ...after which,
> 
> Reviewed-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@...labora.com>
> 

Hello Angelo,

Thanks for your review.
I will modify these in next version.

BRs,
Bo-Chen

> > +
> > +	if (!max_retry)
> > +		return -ETIMEDOUT;
> >   
> >   	ret = mtk_dp_video_config(mtk_dp);
> >   	if (ret)
> 
>